The invention relates to a curved escalator consisting of a stair section, which is curved when viewed in plan and which is provided with a central region with a predetermined constant angle of inclination, upper and lower stair landing regions essentially with an angle of inclination that is zero as well as transition regions which connect the central region with the upper and lower stair landing regions and which are provided with changing angles of inclination for a smooth connection of these regions, wherein in the lower and upper stair landing region a plurality of horizontally disposed steps may be provided, guide curves, which ensure that the step tread in the regions is oriented horizontally, and drive chains that are fixedly linked to the steps and that are provided with a constant length between the steps, consisting of a plurality of chain links for driving the steps on an outer and inner arc, wherein
the arc of the stair section when viewed in plan has a constant radius and the angular velocities of the inner drive chain and of the outer drive chain in this region are the same at any given time, PA1 the arc of the upper and lower stair landing regions when viewed in plan has a constant radius which is made larger compared to R, and the angular velocities of the inner drive chain and of the outer drive chain are the same everywhere in this region as well.
A curved escalator of the type mentioned in the beginning is known from DE-A 34 37 369. With this escalator it is not possible to describe a pure circular arc in all regions, especially in the transition regions. Furthermore, this escalator has gaps between the steps themselves and between the steps and the side walls.
From U.S. Pat. No. 4,949,832 a curved escalator is known in which the drive chain for driving the steps is provided with an additional joint between adjacent steps which is guided over cams on respective cam paths located inside and outside. In the landing zone, step paths and cam paths are located perpendicularly on top of each other, which leads to kinking the drive chains in the landing zone and in the transition zone. This is to accomplish that the horizontal component of the angular velocity of the steps remains constant and that an acceleration of the chains only takes place in vertical direction. The straightening of the drive chains in vertical direction exerts considerable pressure forces on the pivot joints so that a very complex bearing arrangement and guidance of the cam paths is required. Owing to the increased load, wear of the greatly used bearings and guide paths must also be expected.
A straightening of the drive chain is also illustrated in EP-A 390 630 in different variations, wherein, for the reinforcement of the intermediate joints a cam support plate is configured such that it can absorb horizontal as well as vertical forces. Together, the laterally mounted cam support plate, the cams and the protruding axles result in a widening of the drive chain. In the stair platform zones or in the landing zones, this leads to an increased space requirement and a complicated chain guidance, particularly in the region of the drive wheels.
From DE-B 40 36 667 a curved escalator is known in which the respective drive chain is guided on a rail that is separate from the step rail and in which different paths of travel for step and drive chain are made possible by means of a tie rod connecting the drive chain with the step. This accomplishes a precise orientation of the step axle. But at least two guide rails more are required for the guidance of the drive chain provided with the tie rod than for conventional escalators. Moreover, the steps are not held totally secure by the tie rod so that an upward movement, e.g., in case of vibration, can only be avoided by means of additional guide rails.
For the construction of curved escalators it is necessary to precisely determine the course of three-dimensional curves such as, e.g., of guide rails, drive chains and handrails. Even small deviations of 0.0010 mm result in considerable mechanical loads which result in greater wear and increased noise development during the operation of the escalator.
Moreover, the gap enlargements that occur are also not desired. Pursuant to the safety regulations in force the gaps may not exceed a value of 6 mm.
The mechanical implementation of three-dimensional curves in the configuration of a widened circular arc has proven to be particularly difficult. Since their shape is based on empirically gained solutions of approximation, individual component groups cannot be precisely calculated and manufactured. For this purpose, complicated reference planes and systems of coordinates must first be created, which make the construction of such escalators complex, expensive and time-consuming.